1. Field of the Invention
This invention is directed to a bar code scanner of the type used to read bar codes such as U.P.C. bar codes on package labels. These bar codes are used to provide product information to data processing machinery at a point of purchase so that products chosen by a consumer-purchaser may be moved across a horizontal scanning window. The data processing machinery determines the cost of a product by comparing the bar code on the product's label with a list stored in a memory bank. The information stored in the memory bank may include information from a universal commercial list provided for several sale outlets as well as additional information provided at individual sales outlets. Such additional information may include information regarding non-uniform packaging, such as meat and produce at a supermarket. The most common application of this system uses the U.P.C. bar code.
The U.P.C. bar codes are established by the Uniform Grocery Product Code Council which distributes codes which may be used by various wholesale manufacturers. In addition to these designated codes, an individual retailer may apply individual codes, such as those used for products which are not uniformly packaged. The use of the U.P.C. system not only reduces labor cost at the point of sale, but also enables other data processing to be provided. For example, the system is used as a part of a continuing or "perpetual" inventory control, thus necessitating inventory checks only for reduction in inventory outside of the scanning system such as non-scanned sales, breakage, theft and other shrinkage. Additionally, time-of-day sales information and other previously difficult to obtain information may be provided by the system. With the possible development of improved pricing indicators on the market display shelves, it may be possible to further eliminate the step of placing price labels on package labels, thus further reducing labor costs.
When products are passed over a code-scanning window, an approximate alignment of the code label is made by the checkout girl with the center of the scanning window. The scanner must then locate the beginning and end of the encodation on the label, regardless of the direction that the code label is oriented along the surface of the scanning window. Thus, a package carton may be moved across the window with the U.P.C. bar code label aligned in any direction along the lower surface of the carton, provided that the label faces downward and is in the general vicinity of the center of the scanning window. Thus, while a reverse orientation of the bars on a bar code may be interpreted by data processing circuitry, it is also necessary that the scanner be able to read the bars when they are aligned transversely, longitudinally or at an angle to the direction that they are to be passed across the window. 2. Description of the Prior Art
Bar code readers of the type used in supermarkets presently employ a coherent (laser) light source and a mirrored drum in order to scan bar codes. Typical devices using this system are described in Jeffery, et al., U.S. Pat. No. 4,043,632, Tofoya, U.S. Pat. No. 4,057,784 and Nickel, U.S. Pat. No. 4,093,865. The mirrored drum must be rotated at a fairly high speed, such as 1800 rpm U.S. Pat. No. 4,057,784) or 3500 rpm U.S. Pat. No. 4,043,632). Further optics may also be required such as the vibrating mirror assembly of U.S. Pat. No. 4,057,784.
The use of a coherent light source creates problems with regard to maximum allowable emissions, due to the ability of the coherent light source to project a light beam which does not have a significantally reduced intensity as the human eye is moved away from the (coherent) light source. As mentioned in U.S. Pat. No. 4,057,784, federal regulations from such agencies as the Bureau of Radialogocal Health (BRH) must be met. As stated in the patent, there are sometimes difficulties encountered in maintaining sufficient power to obtain an adequate reflection from a low contrast label while keeping the optical emissions of the device at a safe level.
It is expected that various local governments will further restrict the use of laser devices in public areas, in part due to a lack of trust by the local governments for the ability of the federal government to safeguard their citizens from radiation hazards.
U.S. Pat. No. 3,758,753 to Myer shows a code-reading device in which the illuminating source may be comprised of conventional lamps. An array of optical bundles with associated photo multipliers is used, in addition to a first detector which is included for the purpose of providing an output capable of reading various codes. However, the device requires that an optical system rotate at 120 rpm and that a rotating mirrored drum turn at 1800 rpm. It should also be noted that the system is adapted to a label in which a timing reference strip along the length of the coded label is used in order to reference different codes located below the timing reference.
U.S. Pat. No. 4,074,114 to Dobres shows an optical scanner which apparently uses neither a rotating drum nor a coherent light source. While a certain "operating range" is described, it is necessary that the code reader be aligned in a certain direction relative to the code to be read.
Various arrangements have been proposed for producing optically sensitive arrays. For example, U.S. Pat. No. 3,785,753 (cited above) indicates the use of a series of photo multipliers. U.S. Pat. Nos. 3,787,823, 3,860,915 and 3,993,888 also disclose optical elements arranged in matrices, or arranged for the purpose of scanning. However, none of these patents discloses the use of such an array for the purpose of scanning a label in a random orientation without the use of rotating objects.
Accordingly, it is an object of this invention to provide a scanning system which eliminates the drawbacks of prior art scanning devices. These drawbacks include the requirement for moving parts such as a rotating drum, the use of a coherent light source, as well as the requirement that the bar code be aligned in any direction for reading by a scanner.
It is a further object of this invention to provide a label scanner which does not require the use of moving parts, while permitting a label to be passed across the scanner in any direction.
It is a further object of this invention to provide a label scanner which does not use a coherent light source and yet may be used in an environment where labels are passed across the scanner with a bar code aligned in random directions.
It is a further object to provide a bar code scanner in which a non-coherent light source is used and the bar code is focused by stationary optical means to the necessary detectors so that the bar code can be read regardless of the alignment of an encoded label as it is passed across a viewing window.
It is a further object of this invention to provide a bar code label scanner having a stationary window which does not require the use of a coherent light source or the use of moving parts such as a rotating mirrored drum, and which permits a label to be passed over the window in any axial alignment, provided that the label is placed face-downward.